The blown film extrusion process is a vertically oriented extrusion process that requires a structure, commonly called a xe2x80x9cblown film towerxe2x80x9d to host equipment at different elevations and provide physical space to enhance film cooling. The blown film process is a well known type of thermoplastic extrusion process where raw materials such as pellets of solid polyethylene are placed into and gravity fed through a hopper. A feed screw and electric type heater component inside a barrel beneath the hopper further mushes and melts the pellets. A resulting uniform homogenous melted material(having the consistency of a jello type material) is then fed through a coloring dye into the bottom of a blown film tower, where a compressed air supply injects air into a holder forming a film bubble. The resulting bubble rises upward through the middle of the tower to a shaping device such as a hollow funnel adjacent to the top of the tower having a narrow upper opening where a conventional nip and roll assembly on top of the tower allows for resulting film to be pulled out.
Conventional blown film towers are usually custom made for each worksite to specific heights and dimensions. These towers include many raw steel type materials and extensive labor installation time for assembly. Generally, the components of these conventional towers are permanently welded in place. Installing these towers can take up to 45 days or more to assemble and cost up to and over some $400,000 to complete.
U.S. Pat. Nos. 3,980,418 to Schott, Jr.; 4,243,363 to Mulcahy; 4,355,966 to Sweeney et al. and 4,402,656 to Schott, Jr., each show blown film processing systems that use conventional type towers having the types of problems previously described.
Other Patents exist on scaffolding type systems and stair case units that also fail to overcome problems described above. These patents include U.S. Pat. Nos. 3,752,262 to Helms; 3,768,016 to Townsend et al.; 3,807,120 to Viandon; 3,817,347 to Spencer; 4,867,274 to Langer; 5,135,077 to Shalders and 5,491,939 to Wang.
The primary objective of this invention is to provide a modular blown film tower that is customizable for different features. Auxiliary components such as cooling coils, blenders, and the like can be added onto the tower. Floor elevation, stair placement can be adjusted, and additional mezzanine extensions and deck areas can also be expanded or contracted.
The second objective of this invention is to provide a modular blow film tower that is easily changeable. The tower can be reconfigured for a different setup and/or dismantled and moved for relocation purposes.
The third objective of this invention is to provide a modular blow film tower that is quick and simple to install. The novel tower can arrive onsite in a prefabricated kit form that can be fastened together with bolts, and the like, in approximately one to five days(usually encompassing no more than approximately 8 to approximately 30 hours). The bolt type fastened construction minimizes disruptions to existing facilities, and can be planned for installation on the user""s desired schedule.
The fourth objective of this invention is to provide a modular blow film tower that made for the selected worksite. The modular tower would be adaptable and is not isolated from other different existing towers that can exist onsite, since the modular tower allows for width, depth, and elevation adaptability to almost all types of plants. Using two modular towers allows for common servicing for each film line in a plant.
The fifth objective of this invention is to provide a modular blow film tower that allows the ability of the blown film processing user to be able to refit their lines in place. This ability allows the user to easily expand a line widths and/or elevations as their few process opportunities demand changes.
The sixth objective of this invention is to provide a modular tower for processes such as blown film processes that allows the user to use identical column footprints for different levels.
The seventh objective of this invention is to provide a modular tower having adjustable braces such as cross-braces, for stiffening the tower and for reducing swaying and twisting of the tower along with reduced vibrations, when plural platforms are stacked on top of one another.
The eighth objective of this invention is to provide a modular tower having adjustable braces such as cross-braces, for stiffening the tower and for reducing swaying and twisting of the tower along with reduced vibrations, when heavy equipment is placed on the tower.
The ninth objective of this invention is to provide a modular tower having adjustable braces such as cross-braces, for stiffening the tower and for reducing swaying and twisting of the tower along with reduced vibrations, when equipment such as machinery is running on the tower.
The tenth objective of this invention is to provide a modular tower that can use the same backfill(support member) for different sized nip components(i.e. different widths, lengths, etc.), without having to customize a separate backfill and/or separate tower structure for each different sized nip component.
The preferred embodiment of the invention includes a modular multi-level blown film tower that can be fastened together by bolts. The modular tower allows for concurrent erection of the elevated equipment necessary for blown film processing along with the tower itself. This method vastly reduces time and cost of blown film equipment installation. The novel fixed position of the tower columns and known platform area simplifies and eases the electrical wiring and water and air piping of the equipment routed through the tower again reducing time and costs. The modular components for the tower can include core platform segments, handrails, columns, stairs and backfill. Various extensions can be utilized for expanding the platform area for accommodating nip assembly and additional equipment width variability. Easy expansion or contraction optimizes platform areas for tower mounted equipment. Each additional extension level can also consist of platform segments, handrails, columns, stairs and backfill. The stackable assembly method allows for concurrent equipment and platform lifting. This is done by attaching the film equipment to its respective platform at floor level then raising both the platform and the equipment together adding subsequent levels of combinations of equipment and platforms. The stackable assembly method eliminates having to open up a roof of a building in order to place equipment on a previously established tower.
Columns supporting each of the platform levels above the floor are dimensionally fixed despite the width of the nip roll and collapsing assembly. When nip assembly widths encroach on the outer limits of the structure thus eliminating operator access in the cross direction, extensions can be added. Conversely, narrow nip assemblies can be hosted by backfilling the opening with a separate metal(such as steel) insert on the available inside area. The pre-positioned fixed columns and platform dimensions allow for pre-calculated paths for servicing the tower hosted equipment with required wires, air and water pipes/ducts. This advance planning capability is key to reducing equipment installation time and cost. Since buildings using blown film processing varies as to size and dimensions, the modular tower invention allows for variable height levels as needed in order to conform to the available installation space and/or to match the size and dimensions of existing structures.
Adjustable bracing such as cross-bracing having threaded bars, and the like, can be attached to tower legs and to cross members to aid in stiffening the tower when heavy equipment is positioned on the tower, machinery is running on the tower and/or when plural platforms are stacked on top of one another. The adjustable bracing can square off, center, and align the tower. Furthermore, the towers can have reduced swaying, twisting and vibrations over time.